Wall depth, exterior water control, sound goals and drying direction influence foam choice. Open-cell and closed-cell spray polyurethane foams can both create air barriers at product-specific thicknesses, but their density, R-value, vapor behavior, expansion and cost differ.
Open-cell spray foam
Open-cell foam is commonly called half-pound or low-density foam. It expands substantially, conforms around irregular cavities and is typically softer after curing. A typical thermal value is about R-3.6 per inch, but the installed rating must come from the selected product. Open-cell foam remains vapor-permeable and can absorb liquid water, so the assembly must have an intentional drying and humidity-control strategy.
Closed-cell spray foam
Closed-cell foam is commonly called two-pound or high-density foam. It is much denser, expands less and commonly provides roughly R-6 to R-7 per inch depending on the product. It has substantially lower vapor permeance and adds rigidity when bonded to a suitable substrate. Its higher material use and installation demands generally make it more expensive.
| Characteristic | Open cell | Closed cell |
|---|---|---|
| Typical density | About 0.5 lb/ft³ | About 2 lb/ft³ |
| Typical R-value per inch | About R-3.6 | Often about R-6 to R-7 |
| Expansion | Higher; fills irregular cavities readily | Lower; installed in controlled lifts |
| Water-vapor behavior | Vapor-permeable | More vapor-resistant |
| Texture | Softer and flexible | Dense and rigid |
| Relative material cost | Usually lower | Usually higher |
Open-cell strengths
- Expands to fill complex cavities
- Can provide effective air sealing at tested thickness
- Often useful for sound absorption
- May cost less for applications requiring greater thickness
Open-cell limitations
- Lower R-value per inch
- More vapor-permeable and can hold liquid water
- Hot-humid roof assemblies require humidity and drying analysis
Closed-cell strengths
- Higher R-value where space is limited
- Stronger vapor and moisture resistance
- Dense bond can add rigidity to some assemblies
- Often evaluated for metal and container surfaces
Closed-cell limitations
- Higher cost and more material per volume
- Less expansion means application technique matters
- Low vapor permeance may restrict drying in one direction
South Florida decision points
For an unvented attic, the roof deck, indoor humidity, air-conditioning strategy and ability of sheathing to dry matter. For corrugated metal, condensation control and adhesion often push the discussion toward closed-cell foam. For sound-sensitive interior cavities or deep wood framing, open-cell foam may be considered. Neither product fixes bulk water entry, unsafe equipment or uncontrolled interior humidity.
R-value is only one design variable
A high R-value does not compensate for gaps, wrong placement, trapped water, unsafe clearances or a missing air-control strategy. Ask how the full assembly manages heat, air, vapor and rain.
Compare by application
Review open-cell foam in attics, closed-cell foam in attics, foam choices for containers, metal building insulation and wall insulation before requesting an application-specific estimate.
Frequently Asked Questions
How do I request a Open Cell vs Closed Cell Foam for Walls estimate?
Use the estimate form with the property ZIP code, approximate size, project type, existing insulation and preferred contact method, or call (305) 684-3580.
Does Insulation Aces serve my area?
Insulation Aces serves Miami-Dade County, Broward County and the Florida Keys.
Can you recommend insulation from square footage alone?
Square footage helps with planning, but access, existing conditions, moisture, material, thickness and preparation also affect the recommendation and price.